C
ancer has always figured uniquely in the diseases of mankind. For
centuries people spoke of it only in whispers, or not at all, as if the
disease were not only dreadful but somehow shameful as well. Today, the
picture is changing rapidly. More than half of those diagnosed with cancer
will reach the important five-year survival landmark. (The five-year
survival rate is a common measure of progress in the early detection and
treatment of cancer.) Also, much of the mystery that cloaked the disease
has been dissipated.

Of course, cancer remains a formidable enemy. Cancer is the second leading
cause of death in the United States; it causes one in four deaths. Some
1.2 million new cases of cancer are diagnosed annually in the United
States, and an estimated 560,000 people die of it each year. The National
Institutes of Health estimate that cancer costs society more than
$100 billion annually, in terms of direct medical costs and loss of
productivity.

But in context, the picture is not as bleak as it might seem. At the
beginning of the twentieth century, survival from cancer was relatively
rare. At the end of the 1930s, the five-year survival rate was one in five
or fewer. Ten years later it had shot up to one in four, and in the
mid-fifties to one in three. The survival rate for some of the more
widespread cancers has leveled off despite the best efforts of physicians
to devise better forms of treatment. For such cancers, which include those
of the breast, colon, and rectum, improvements will come through earlier
detection and even prevention. Dr. Richard S. Doll, Professor of Medicine
at Oxford University, has said that we could prevent 40 percent of
men's cancer deaths and 10 percent of women's simply by
applying what we already know. For example, according to the American
Cancer Society, the risk of death from lung cancer is 15 to 20 times
greater among men who smoke cigarettes than among men who have never
smoked. The relative risk of lung cancer among women smokers is five times
that of women who have never smoked.

Considerable progress is being made on many fronts in the war against
cancer. It ranges from advances in early detection to breakthroughs in
treatment. Between 1955 and 1992, for example, the death rate from
cervical cancer—which used to be one of the most common causes of
death in American women—declined by 74 percent, mostly because of
the widespread use of the Pap test, which can detect the disease at an
early stage. At the same time, children with acute lymphocytic leukemia,
which used to be invariably fatal in weeks or months, have benefited from
new therapies. The probability of an extended remission or cure was more
than 75 percent in the mid-1990s; it was just 5 percent in 1960. Similar
advances in the treatment of a cancer of the lymph system called
Hodgkin's disease
have improved the five-year survival rate from 25 percent at the end of
World War II to about 81 percent today.

Major Forms of Cancer

T
he following material includes discussions of the major forms of cancer
with the exception of those cancers that affect women only. For
additional information on many kinds of tumors for which surgery may be
indicated, see also Ch. 20,
Surgery
.

Detection

X rays of the stomach and examination of the stomach interior by
gastroscopy usually locate and define the cancerous area; they may also
reveal another cause of the symptoms, such as a peptic ulcer. During the
physical examination, the physician may find a tissue mass and tenderness
in the stomach area. The laboratory report usually will show signs of
anemia from blood loss, the presence of blood in a stool sample, and the
level of hydrochloric acid in the stomach; a lack of hydrochloric acid is
found in more than half the stomach cancer patients. A biopsy study of the
suspected tissue usually completes the diagnosis.

Therapy

Unfortunately, because of the insidious nature of stomach cancer, the
disease becomes easier to diagnose as it progresses. By the time cancer
has been confirmed, the most expedient form of treatment is surgery to
remove the affected area of the stomach. If the cancer is small and has
not spread by metastasis to lymph nodes in the region, the chances are
relatively good that the patient will survive five years or more; the odds
against surviving five years without surgery are, by comparison, about 50
to 1 at best. Chemotherapy treatments may be used in cases where surgery
is not feasible, but the use of medicines instead of surgery for stomach
cancer is not a routine procedure and generally is not recommended.

Occasionally, a stomach tumor is found to be noncancerous. The tumor may
be a polyp, a
leiomyoma
(a growth consisting of smooth muscle tissue), or a
pseudotumor
(false tumor), such as an inflammatory fibroid growth. Such benign tumors
produce symptoms ranging from gastric upset to internal bleeding and
should be removed by surgery.

Causes

Many possible factors have been suggested as causes of stomach cancer.
Dietary factors include hot food and beverages, as well as fish and smoked
foods. Food additives have been implicated despite the fact that the
incidence of stomach cancer has been declining during the period in which
the use of additives has been increasing. Cured meats and cheeses,
preserved with nitrites to retard spoilage, reportedly foster the
development of carcinogenic chemical compounds in the digestive tract.

On the other hand, the widespread use of refrigeration has been offered as
an explanation for the declining incidence of stomach cancer, since
refrigeration reduces the need for chemical food preservatives.

Beyond the influence of diet, medical epidemiologists have found that
genetic factors may play a role in the development of stomach cancer.
Statistical analysis of large population studies of stomach cancer shows a
tendency for the disease to occur in persons with blood type A, or with
below-normal levels of hydrochloric acid in the stomach, or with inherited
variations in the stomach lining. There also seems to be a good
possibility that stomach cancers evolve from noncancerous changes in the
stomach lining, as from polyps or peptic ulcers.